Velocity collision detection (2D)
- by ultifinitus
Alright, so I have made a simple game engine (see youtube)
And my current implementation of collision resolution has a slight problem, involving the velocity of a platform.
Basically I run through all of the objects necessary to detect collisions on and resolve those collisions as I find them. Part of that resolution is setting the player's velocity = the platform's velocity. Which works great! Unless I have a row of platforms moving at different velocities or a platform between a stack of tiles....
(current system)
bool player::handle_collisions() {
collisions tcol;
bool did_handle = false;
bool thisObjectHandle = false;
for (int temp = 0; temp < collideQueue.size(); temp++) {
thisObjectHandle = false;
tcol = get_collision(prevPos.x,y,get_img()->get_width(),get_img()->get_height(),
collideQueue[temp]->get_position().x,collideQueue[temp]->get_position().y,
collideQueue[temp]->get_img()->get_width(),collideQueue[temp]->get_img()->get_height());
if (prevPos.y >= collideQueue[temp]->get_prev_pos().y + collideQueue[temp]->get_img()->get_height())
if (tcol.top > 0) {
add_pos(0,tcol.top);
set_vel(get_vel().x,collideQueue[temp]->get_vel().y);
thisObjectHandle = did_handle = true;
}
if (prevPos.y + get_img()->get_height() <= collideQueue[temp]->get_prev_pos().y)
if (tcol.bottom > 0) {
add_pos(collideQueue[temp]->get_vel().x,-tcol.bottom);
set_vel(get_vel().x/*collideQueue[temp]->get_vel().x*/,collideQueue[temp]->get_vel().y);
ableToJump = true;
jumpTimes = maxjumpable;
thisObjectHandle = did_handle = true;
}
///
/// ADD CODE FROM NEXT CODE BLOCK HERE (on forum, not in code)
///
}
for (int temp = 0; temp < collideQueue.size(); temp++) {
thisObjectHandle = false;
tcol = get_collision(x,y,get_img()->get_width(),get_img()->get_height(),
collideQueue[temp]->get_position().x,collideQueue[temp]->get_position().y,
collideQueue[temp]->get_img()->get_width(),collideQueue[temp]->get_img()->get_height());
if (prevPos.x + get_img()->get_width() <= collideQueue[temp]->get_prev_pos().x)
if (tcol.left > 0) {
add_pos(-tcol.left,0);
set_vel(collideQueue[temp]->get_vel().x,get_vel().y);
thisObjectHandle = did_handle = true;
}
if (prevPos.x >= collideQueue[temp]->get_prev_pos().x + collideQueue[temp]->get_img()->get_width())
if (tcol.right > 0) {
add_pos(tcol.right,0);
set_vel(collideQueue[temp]->get_vel().x,get_vel().y);
thisObjectHandle = did_handle = true;
}
}
return did_handle;
}
(if I add the following code {where the comment to do so is}, which is glitchy, the above problem doesn't happen, though it brings others)
if (!thisObjectHandle) {
if (tcol.bottom > tcol.top) {
add_pos(collideQueue[temp]->get_vel().x,-tcol.bottom);
set_vel(get_vel().x,collideQueue[temp]->get_vel().y);
}
else if (tcol.top > tcol.bottom) {
add_pos(0,tcol.top);
set_vel(get_vel().x,collideQueue[temp]->get_vel().y);
}
}
How would you change my system to prevent this?
